Whitening composition for paper



Fateuted Dec. 12, lldfil ord lea, Wiln ngton, gnors to ll. du Pont deNeuron-rs and Company, Wild: rgton, Del, a corpora on oi 13" "re NoFiled Apr. 7, 1959, Ser- No. 394,597

6 (til. TEE-3M2) This invention relate to an improved Whitening composition for us whitening paper. it is an object of this true tion toprovide a composition of matter for the aforementioned purpose which isin the form of a concentrated aqueous solution, adapted to be diluted toThis compound may be named 4,4-bis-[2 phenylamino4-diethanolamino-1,3,5-

wherein X is H, Na or K.

tr 231(6)1 laminostilbcne-2,2-disulionic acid, or an alkali-metal saltthereof. The preparation of agent and other related compounds isdescribed in US. Alien Property Custo specification Serial No. 381,856,published May 11, 1943.

it has been observed, however, that for obtaining good whitening effectson paper, borax or tetrasodium pyrophosphate must be used in conjunctionwith the above fluorescent. Thus, good results may be obtained by dipgpaper in sheet form into an aqueous dye bath, Iormed by dissolving inwater certain dry compositions containing the said fluorescent andtetrasodium py rophcsphate in powder form, then squeezing out ordrainexcess moisture and drying the sheets. However, this procedure haspractical (L'sadvantages when applied on a plant scale, largely due tothe diifioulty of dissolving the powder the treating bath and because ofthe tency to spread dusts in the surrounding atmosphere.

We now that concentrated solutions of the whitenabove formulated,characterized by good sta- -'.tty in storage, easy dilutability withwater and relv poten whitening enacts of the resulting dye itening agentof the aforegoin formula an i of the general formula (IlO-alk) -NR ad;is an alkylene radical of 2 to 4- C-atoms, R

r l to 3. Typical, commercially availalkylolamines which come under themonoethanolamine, diethanolamine, non g mono-, dior triprolnos (normalor iso); the corresponding butanol- Ars t amines (normal, iso or tert.;mono, di or tri); N-methyl diethanolamine; N,N-dirnethyl ethanolamine,N,N-diethyl ethanolarnine, NN-diisopropyl ethanolamine, and N,N-di(2-ethylhexyl) ethanolamine.

The proportion by Weight of the alkylolamine agents to Whitening agentmay vary widely, say from 0.5:1 to 3.011 and is preferably determinedexperimentally, the minimum practical quantity of the alkyiclamine beingthat which will effect complete solution in Water (as far as judged bythe naked eye) of the desired quantity of whitening agent, to give amarketable concentrated aqueous solution of the same.

More particularly, the concentrated Whitening agent solutions of thisinvention will generally contain from to 10% by weight of the saidwhitening agent, from 5% to 35% by Weight of said alkylolamine, aninevitable residual quantity of sodium chloride which is inherent in thesynthesis recovery of the whitening agent, the remainder of solutionbeing water. For best results, however, the bull; of the salt content ofthe whitening agent is removed before preparation of the solution, andcare is taken that the residual quantity shall not exceed 1% by Weightof the concentrated solution. The water content of the concentrate willaccordingly vary from about 30% to about 85% by Weight.

The liquid concentrate described above is a clear light yellow or ambersolution which is stable to storage over the range of temperaturesnormally encountered; i.e., Warehouse temperatures in summer and Winter.Sometimes a slight separation of components may occur at Wintertemperatures, but on warming to room temperature for use, completesolution is again obtained. I

This solution can be readily diluted at room temperature. For practicaluse, it is diluted to give an ultimate whitening agent concentration ofabout 0.05% to 0.10%. Paper in the form of sheets may then be immersedin the dye bath, freed of excess water, and dried.

The unforeseen effect of the mentioned alkylolamines on the potency ofthe solution as a whitening agent is particularly remarkable when it isconsidered that other known solutions of the same whitening agents (cg.Cellosolve solutions) give a relatively poor whitening eifect whenapplied to paper sheets by the above procedure. On the other hand,Cellosolve (lower alkyl others of ethylene glycol) or other alcoholicagents may be added, without ill effect, to our novel concentratedsolution, in optional proportions, so long as the alkylolamine fluorescent ratio stays Within the limits above noted, i.e. from 0.521 to3.021. Ratios larger than 3.0:1 may be used, but simply add to the costof the-solution.

Without limiting this invention, the following examples are given toillustrate our preferred mode of operation. Parts mentioned are byWeight.

Example 1 76.2 parts of a press cake containing 25 parts of 4,4- bis- [2phenylamino-4-diethanolamino-1,3 ,5 -triazyl 6) diaminostilbenedisulfonic acid and 1.2% NaCl is mixed at room temperature with 37.8parts of tr'ethanolamine and 7.2 parts of water. The resulting solutionis filtered with the aid of Filter-Col and contains by analysisaptechnique using a dry formulation of whitening agent of proximately21% by Weight of the dye, 31% by Weight the following composition: oftriethanolamine and 0.68% sodium chloride. (This Parts corresponds to analkanolaminezwhitening agent ratio The fluorescent above formulated (Nasalt) 12 of 9.1:1 in moles.) The solution does not cloud even 5 Sugar 85at temperatures as low as 0 C. Soda ash 3 When the above solution isdiluted with water at room temperature to a concentration of 0.05% byweight of Total 100 the whitening agent, and paper sheeting, forinstance sized White cover board, is dipped into the solution, squeezedand dried at 180 F., the paper is found to be very white and bright andacceptable for commercial use.

When the same paper is treated at the same strength Example 6 2: Zigfiig g s gfi g i g ii ggig g agent A mixture of 13.5 parts oftriethanolarnine, 25 parts the treat d a a d d h yo i press of thewhitening agent (76.2 parts of press cake confi P PVT u an as a ye OwlsGas tainlng 25 parts of agent and 1.2% NaCl) and water to Example 2 make200 parts total is heated at 70 to 75 C. until solution is complete.This solution thus contains 6.75% triethanolamine and 12.5% of theWhitening agent, which corresponds to a mole ratio of about 3.3:1, inthe order named. This solution is stable to storage and, when it isdiluted with water to a dye concentration of 0.1%, it gives satisfactorywhitening effects on paper.

It will be understood that the details of this invention may be variedwidely without departing from the spirit thereof. I

This application is a continuation-in-part of our application Serial No.672,107, now abandoned, filed July 16, 1957.

We claim as our invention:

1. A composition of'matter for whitening paper, con- The said heatertechnique, more over, required a beater concentration of the abovecomposition equivalent to 0.25% by weight of the active ingredient.

A mixture of 417 parts of the crude whitening agent in the form of itssodium salt (containing 165 parts of the active ingredient), 316 partsof triethanolamine and 267 parts of water are mixed at 60 C. for 2.5hours, and after cooling to 15 to 20 C., the mass is filtered with aidof super-cell. The resulting solution contains 16.5% by weight ofwhitening agent, 31.7% of triethanolamine and 1.0% salt.

When this solution is diluted to a concentration of 0.1% by weight ofthe Whitening agent and paper is treated therewith as in Example 1, theresulting paper possesses a commercially acceptable quality of whitenessand brightness.

Example 3 sistrng essentially of a concentrated aqueous solution of Asolution is prepared as in the above examples to a whitening agent andan alkylolamine and being adapted contain by Weight of monoethanolamine,12% of U to be diluted with water to give an aqueous treatment thewhitening agent in the form of the free acid and bath, said compositionbeing the product of mixing to- .0.18% salt. The solution is stable tostorage, and on gether water, a whitening agent of the formula N N lHN-C G- NH CH=CH -NH-C C-Nl-l i i i i- S aX SOsX a C C l'iKCzHlOH): Dl'(C2H OI-I)2 evaluation on paper at a concentration of 0.1% dye,wherein X stands for a member of the group consisting gives satisfactorywhitening efiects. of hydrogen and the alkali metals, and analkylolamine Essentially the same results are obtained if the monoof theformula (HO-alk) NR wherein alk is an ethanolamine in this example isreplaced by an equal alkylene radical of 2 to 4 C-atoms, R is a memberof the weight of mono-, dior tripropanolamine, normal or iso. groupconsisting of hydrogen and alkyl radicals of 1 Thealkanolamine:whitening agent mole ratio in this to 8 C-atoms, while x isan integer from 1 to 3, said example calculates to 44:1 whenmonoethanolamine is whitening agent being present in quantity from 35%to used and to 14:1 when the same weight of tripropanol- 10% by weightof the entire mixture, said alkylolamine amine i e loyed, being presentin quantity sufficient to effect dissolution Example 4 of said whiteningagent in the aqueous mixture but not less than 3.3 moles per mole ofsaid whitening agent, and said composition being free of sodium chlorideexcept in a quantity not exceeding 1% by weight of the entire mixture.

2. A composition of matter as in claim 1, the quantity of saidalkylolamine being from 5% to 35% by weight of the entire mixture.

3. A composition of matter as in claim 1, said alkylolamine being anethanolamine.

4. A composition of matter for whitening paper in sheet form and beingan aqueous concentrate resulting A solution comprising 35% by weight ofwhitening from mixing of water, monoethanolamine and a whiten- :agentand 35% of triethanolamine (which corresponds 70 ing agent of theformula set forth in claim 1, said whiten- -to an alkanolaminezdye ratioof 6.55:1 in moles) was ing agent being present in quantity from 35% to10% by A solution comprising 24% by Weight of diethanolamine and 18.8%of the whitening agent was diluted to .a concentration of 0.05% of thewhitening agent and evaluated on paper asin Example 1. It was foundsatisfactory.

Essentially the same results are obtained if the diethanolamine in thisexample is replaced by an equal weight of N-rnethyl diethanolamine ordi(2-ethylhexyl)- ethanolamine.

Example 5 evaluated on sized, White cover board at a concentrationweight of the entire mixture While the monoethanolamine .of 0.1%whitening agent in the dye bath. The resulting is present in quantitysufiicient to effect dissolution of said paper Was found to be ofsatisfactory whiteness and fully whitening agent in the aqueous mixturebut not less .equivalent to a commercial paper obtained by the beaterthan 3.3 moles per mole of said whitening agent, said concentratedcomposition having the appearance of a clear, light yellow to ambersolution Which is stable in storage at room temperature and beingadapted to be diluted with water to give an aqueous treatment bath forsaid paper sheets.

5. A composition of matter for Whitening paper in sheet form and beingan aqueous concentrate resulting from mixing of water, a concentratedaqueous solution diethanolamine and a whitening agent of the formula setforth in claim 1, said whitening agent being present in quantity from35% to by Weight of the entire mixture while the diethanolamine ispresent in quantity sufficient to effect dissolution of said whiteningagent in the aqueous mixture but not less than 3.3 moles per mole ofsaid whitening agent, said concentrated composition having theappearance of a clear, light yellow to amber solution which is stable instorage at room temperature and being adapted to be diluted with waterto give an aqueous treatment bath for said paper sheets.

6. A composition of matter for whitening paper in sheet form and beingan aqueous concentrate resulting from mixing of water triethanolamineand a whitening agent of the formula set forth in claim 1, saidwhitening agent being present in quantity from to 10% by weight of theentire mixture while the triethanolamine is present in quantitysuflicient to efiect dissolution of said whitening agent in the aqueousmixture but not less than 3.3 moles per mole of said whitening agent,said concentrated composition having the appearance of a clear, lightyellow to amber solution which is stable in storage at room temperatureand being adapted to be diluted with water to give an aqueous treatmentbath for said paper sheets.

References Cited in the file of this patent UNITED STATES PATENTS2,878,248 Crounse Mar. 17, 1959 FOREIGN PATENTS 647,718 Great BritainDec. 20, 1950 128,651 Australia Mar. 16, 194-5 OTHER REFERENCES Ser. No.381,856, Wendt (A.P.C.), published May 11, 1943.

Patent No 8 Ol2 97l December 12 1961 Joseph Gessner e't als correctedbelow Column 5 line 8 strike out "a concentrated a ueous 0 1 a Qs0lut1on"; line 22 after "v-water" insert, a commae Signed and sealedthis 17th day of April .1962,

(SEAL) Attest:

ESTON e. JOHNSON DAVID Lo LADD Attesting Officer Commissioner of Patents

1. A COMPOSITION OF MATTER FOR WHITENING PAPER, CONSISTING ESSENTIALLY OF A CONCENTRATED AQUEOUS SOLUTION OF A WHITENING AGENT AND AN ALKYLOLAMINE AND BEING ADAPTED TO BE DILUTED WITH WATER TO GIVE AN AQUEOUS TREATMENT BATH, SAID COMPOSITION BEING THE PRODUCT OF MIXING TOGETHER WATER, A WHITENING AGENT OF THE FORMULA 